Track-circuit system



W. W. MACFARLANE. TRACK CIRCUITSYSTEM. APPLICATION FiLED Senzo. 1917. RENEWED Nov. 26, 1920. ,383,320.

Patented July 5, 1921.

Jwventoz UNITED STATES PATENT OFFICE.

WILLIAM W. OF ELKINSPARK, IPENNSYLVANIA, ASSIGNOB '.[0 MAC- FARLANE COMMUNICATIONS CORPORATION, OF YORK, N. Y., A. CORPORATION OF DELAWARE.

TRACK-CIRCUIT SYSTEM.

Specification of Letters Patent.

Original application filed March 8, 1916, Serial no. 82,861. Renewed March 10, 1919, Serial No. 281,816. Divided and this application fl1ed'September20, 1917, Serial No. 192,296. Renewed November 26,

1920. Serial No. 426,609.

To all whom it may concern Be it known that I, WILLIAM W. MACFAR- LANE, a citizen of the United States, and a resident of Elkins Park, in the county of Montgomery .and State of, Pennsylvania, have invented certain new and useful Improvements in Track-Circuit Systems, of which the following is a specification.

This invention relates to railway signaling and more particularly to a system of track circuits adapted to be used for instance in connection with the automatic train controlling apparatus as shown in application Ser. No. 82,861, filed March 8, 1916, now renewal application, Ser. No. 281,816, filed March 10, 1919, of which this application is a division.

The principal object of the invention is to provide means, in a train controlling system in which trafiic controlling apparatus on the train is directly, governed by the condition of the circuit in the track rails, for modifying the condition of the track circuit in the sections of the track immediately to the rear of a train-occupied section so as to exercise.

control over a train entering such sections.

\Vith this and other objects in view, the invention consists principally in the provision of means for supplying current to each section of a track, and of means controlled by the current supplied by each section for somodifying the current supplied to the section next to the rear of the trainoccupied section as to exercise control over a train entering that section. Other features of the invention will appear as the specification proceeds.

In the specific form of the invention chosen for illustration,the single view of the drawing represents a general diagrammatic view of a track circuit system embodying the invention.

In the drawing, the track rails 1 and 2 are shown as divided into suitable block sections A, B, C, D and E that are electrically separated from each other by insulated joints 3 in a manner well known in the art.

Each block is provided at the exit end with asourcesof current 4 normally connected through a conductor 5, contacts 6,

conductor 7, armature 22 and conductor 8 to the track rail 2, and through the conductor 9. including the resistance 10, armature tor 12 leading from the track rail'2 at the entrance end of the block, a pole'changing relay13 and conductor 14 connected in turn to track rail 1. A circuit-controlling relay 15 is connected by means of the branch conductors 16 and 17 to conductors 12 and 1 1 respectively, so that the two relays 13 and 15 are arranged in parallel relation to'each other. The comparative resistance values of the relays 13 and 15 are such that with a certain volume of track current the circuit controlling relay 15 can be energized without simultaneously energizing the corre spinding pole-changing relay 13.

The circuit controlling relay 15 in its energized condition actuatcs the circuit closer 18 to bridge contacts 6 and close the normal or primary track circuit in the next adjacent section.

In the deenergized condition of the relay 15, the circuit closer 18 breaks, contact'with contacts 6 and moves into bridging engagement with contacts 17 to close a circuit in the next adjacent section through a branch comprising conductors 28 and 20 and resistance 19.

The pole-changing relay 13 in its energized condition brings the armature 22 into engagement with contacts 23 and 24. This serves to connect conductors 7 and 8 and conductors 11 and 9 so that they will form part of the normal or primary track circuit already referred to. In the denergized condition of this relay, the armature 22 engages the lower.- contacts 25 and 26. This serves to connect conductors 27 and 11 and conductors 8 and 21 to establish a circuit in the reverse direction when relay 15 is energized to bridge contacts 6.

The presence of a train, indicatedat T in block section B, will have the result of short circuiting relays 13 and 15 connected to the rails in blocksection B and this will result Patented July 5, 1921.

in breaking the normal track circuit and establishing the secondary circuit in block section C. current source 4, conductor 5, contacts 17, conductor 28, resistance 19, conductor 20, track rail 1, conductor 14, conductor 17, relay 15, conductor 16, conductor 12, track rail 2, conductor 8, conductor 21. conductor 9 and resistance 10 back to battery 4. The inclusion of the two resistances 10 and 19 in series With each other in this circuit so affects the volume of current flowing in the circuit that relay 13 of section C remains deenergized while the re lay 15 is energized to actuate the circuit closer 18. This circuit in block section C will energize the corresponding relay 15 to bridge contacts 6 in the normal track circuit of block section D, as will be seen. However, the deenergization of the polechanging relay 13 connected to the rails of the block section C acts to reverse the polarity of the circuit including the track rails of section D so that, while the current has the same relative volume that it has under normal conditions, the direction of flow of the current is reversed and the tendency is for the current to flow from rail 1 to rail 2, instead of from rail 2 to rail 1, as is the case under wholly normal conditions. The circuit thus established is as follows.

Current source 4, conductor 5, contact 6, conductor 7, conductor 27, armature 22, conductor 11, track rail 1, conductor 14, relays 15 and 13. conductor 12, track rail 2, conductor 8. armature 22, conductor 21, conductor 9, resistance 10 and back to battery 4. It will be seen that by use of this system of track circuits the volume of current sup plied to the rails of the section immediately to the rear of a train-occupied block is greatly diminished because of the necessity for this current flow to take place through the interposed resistance 19. It will also be seen that the character of the current flowing through the rails of the second section to the rear of the train-occupied block is also modified, in that the flow of current in this section takes place in reversed direction. These two modifications of the track circuit, including the rails of the two sections immediately preceding a train, have been made use of to represent conditions of caution and danger and to automatically control the movement of a train in accordance therewith in the parent case, Ser. No. 82.861, now Ser. No. 281,816 to which reference has been made.

I claim:

1. A track circuit system comprising track rails divided into insulated sections, means for supplying current to the rails of each section, a pair of relays for each section controlled by current from said current suption, a pair of relays for each section controlled by current from said current supplymg means of their own section, a ClICIlltIG- versing device in each section operated by one of said relays of the preceding section,

the other of said relays being adapted to modify the current supplied to the next adjoining section to thereby control the circuit reversing device operating relay of the second adjoining section.

3. A track circuit system comprising: track rails divided into sections, means for supplying a comparatively large volume of current to the exit end of each section, a pair of relays connected in parallel to the rails at the entrance end of each section, one of said relays being arranged to diminish the volume of current supplied to the adjacent exit end of the next adjoining section when said relay is deenergized, and the other relay being arranged to reverse the di rection of flow of the current supplied to the second adjoining section when the intervening section receives the lessened volume of current. V

4. A track circuit system comprising: track rails'divided into sections, means for supplying current to the exit end of each section, a pair of relays connected in parallel to the rails at the entrance end of each section, one of said relays being arranged to diminish the volume of current supplied to the adjacent exit end of the next adjoining section whenthe relay is denergized, and the other relay being arranged to reverse the direction of flow of the current supplied to thesecond adjoining section when the intervening sect-ion receives the lessened volume of current, said relays having such relative resistance values that the diminished volume of current in the intervening section is sufficient to restore the current volume controlling relay of said intervening section to normal but is not sufiicient to restore the circuit reversing relay of said intervening section to normal.

Signed at New York, in the county of New York and State of New York, this 18th day of Sept. 1917.

WILLIAM W. MACFARLANE. 

